Conventionally, a camera device such as a surveillance camera has used a complementary color CCD (an image pickup device having a complementary color filter) in order to increase the sensitivity of the camera. In such a conventional camera device, color parameters are set according to the spectral sensitivities of the complementary color CCD, and color calibration (calibration) is performed using the color parameters (e.g., see Patent Literature 1). The values of the color parameters are usually set according to illumination conditions of so-called standard light sources (e.g., a color temperature 3200 K).
However, in the conventional camera devices, because color parameter values are set according to illumination conditions of standard light sources (e.g., a halogen light of a color temperature 3200 K), if an illumination condition is changed, a color phase shift occurs and suitable color calibration is not performed. For example, if a color temperature of a light source is extremely low (especially, under an illumination condition close to a near-infrared light such as illumination in tunnels), although an actual color is whitish, suitable color calibration is not performed, resulting in an orangish color.
Thus, it is contemplated to calibrate a difference of a color parameter by using a technique that specifies any color parameter value in a three-dimensional color space (a color space of luminance in one dimension and chrominance in two dimensions). However, there are innumerable color parameters based on primary colors and complementary colors (e.g., three primary colors of “R,” “G,” and “B” and three complementary colors of “Cy,” “Mg,” and “Ye”) as well as a calibration amount for a color parameter is different for each color temperature. Therefore, since a data amount of a table storing calibration amounts for all color parameters for each color temperature would be enormous, it is difficult to say that this table is practical.